Effect of operating conditions on the chemical composition, morphology, and nano-structure of particulate emissions in a light hydrocarbon premixed charge compression ignition (PCCI) engine

The aim of present work is to bridge the gap of knowledge concerning crystallite size, graphene layers curvature and inter-layer distance as nanostructure characteristics of soot primary particles, and also to comprehensively characterize the morphology of soot emission in a light hydrocarbon premixed charge compression ignition (PCCI) engine. In this study, the chemical composition, morphology and nano-structure of particulate emissions between conventional diesel and light hydrocarbon PCCI engine were performed with thermogravimetric analysis, gas chromatography mass spectrometry, and high-resolution transmission electron microscopy technology. The results show that the volatile matter content of light hydrocarbon is much higher than that of diesel, and thermogravimetry and differential thermogravimetry curves of light hydrocarbon shift to low temperature regions. The total organic components of particulate matter of light hydrocarbon PCCI engine are less, and the corresponding separation time is shorter. The structure of particles produced in light hydrocarbon PCCI engine is more open, and the size of aggregates is smaller. Fractal dimensions of 1.774 and 1.691 are obtained for soot particles in light hydrocarbon PCCI engine, compared to that of 1.81 and 1.785 in conventional diesel engine. Compared to conventional diesel engine, fringe separation distance and fringe tortuosity in light hydrocarbon PCCI engine are smaller while fringe length is larger. The primary particle nanostructures of light hydrocarbon PCCI engine incline to graphitize and change into the orderly structure. Compared with conventional diesel combustion, the average primary particle diameter of light hydrocarbon PCCI approximately reduces 2.0% at 75% load and 18.2% at 100% load, respectively.

Microstructure-based non-Fourier heat transfer modeling of HIFU treatment for thyroid cancer

BACKGROUND AND OBJECTIVES

High intensity focused ultrasound is an emerging non-invasive technique for the thermal ablation of cancer. Modeling of high intensity focused ultrasound as a method to induce hyperthermia, by considering non-equilibrium convective heat transfer has been under-represented in the previous studies. Therefore, in the present study, we aimed to study the effect of blood vessels during high intensity focused ultrasound ablation of thyroid cancer. In addition, high intensity focused ultrasound modeling was greatly improved by considering non-Fourier heat transfer.

METHODS

The modified dual-phase-lag model was used for the modeling of heat transfer in thyroid cancer during the ultrasound irradiation. The model parameters were linked with the tissue's microstructure parameters. Meanwhile, an interfacial convective heat transfer was considered between the blood vessels and the extravascular matrix. The extent of the vascular region was determined using the field emission scanning electron microscopy images. The non-linear Westervelt equation was solved for the sound wave to determine the heat source for the induced hyperthermia treatment.

RESULTS

Referring to the acoustic results, sharp-wave ripples were observed due to the inclusion of notable amplitudes of excited harmonics. The thermal results showed a maximum temperature rise of 25.08°C and 51.47°C at the powers of 5 W and 10 W using the modified dual-phase-lag model, while the Pennes model predicted a temperature rise of 28.77°C and 55.5°C at the same powers. It was also concluded that a constant blood temperature, overestimates the dissipated energy and the temperature reduction during the cooling period, as a 15% deviation in the tumor temperature was observed from the non-equilibrium state at 10.65 s exposure and 10 W power. Eventually, the calculation of the ablated volumes indicated that the volumes were up to 4.5 times larger by the Pennes model compared to the modified dual-phase-lag model.

CONCLUSIONS

It can be concluded from the results that there should be a serious concern on the high intensity focused ultrasound modeling based on the parameters of blood vessels. Based on the thermal maps, the cancerous tissue should be exposed to a higher energy level of ultrasound waves in order to cause the desired damage against the estimated energy level predicted by the Pennes model.

Nanoscale infrared, thermal and mechanical properties of aged microplastics revealed by an atomic force microscopy coupled with infrared spectroscopy (AFM-IR) technique

Microplastics (MPs) often undergo different degrees of aging, and the aged MPs exhibit different surface properties from pristine MPs. This study explored the nanoscale infrared, thermal and mechanical properties of TiO₂-pigmented MPs before and after aging by using an AFM-IR technique. Results showed that the surface of MPs was relatively smooth before aging, and was rough with more granular domains after aging. The stronger band at 1706 cm^-1 (assigned to CO) and the weaker band at 1470 cm^-1 (assigned to -CH₂) were observed in aged MPs due to oxidation of CH bond in low-density polyethylene (LDPE). The softening temperature of MPs was about 209.50 ± 11.48 °C before aging, but after aging it dropped to 94.91 ± 4.40 °C. Aging process mainly reduced the glass transition temperature of the continuous phase (LDPE) rather than the discrete phase (TiO₂) in MPs. Resonance deviations of the two characteristic peaks (i.e., 299/645 kHz and 311/670 kHz) between unaged and aged MPs were observed, and these characteristic peaks obviously appeared at higher frequencies in aged MPs, suggesting that the MPs after aging became stiffer. A stronger signal at a high frequency and the uniform signal distribution at this frequency confirmed that the mechanical properties of MPs changed after aging. These findings help to better understand the effects of aging process on the physicochemical properties of MPs.

Facile synthesis of a high efficiency and durability L-citrulline flame retardant for cotton

A novel flame retardant (FR), the ammonium salt of citrulline-penta (methylphosphonic acid) (ACPMPA) based on L-citrulline was synthesized, and its structure was characterized by ¹³C, ¹H, and ³¹P nuclear magnetic resonance (NMR) spectroscopy. The ACPMPA flame retardant molecule contains five ammonium salts of phosphorus acid and one ammonium salt of carboxylic acid, which allowed the covalent attachment of ACPMPA onto cellulose via -P=O(-O-C) and -COOC bonds. The results showed that the treated cotton fabrics had very high flame retardance and excellent durability. The limiting oxygen index (LOI) of cotton fabric treated with 35%-ACPMPA reached 49.2% and only decreased to 34.2% after 50 laundry cycles. Vertical flame tests also demonstrated that the treated cotton fabric acquired good flame retardance. The thermogravimetry (TG) and TG-IR results showed that the treated cotton left more residues and released almost no flammable volatiles at high temperatures. The cone calorimetry results showed that the treated cotton released less heat than pure cotton. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results demonstrated that the structure of the treated cotton fabric was almost unchanged, and no free formaldehyde was detected, indicating that the treated cotton was safe. The treated cotton fabric also retained good tensile strength and whiteness.

Room Temperature Intrinsic Emission Ratio of BSA Correlates With Percent Aggregates During Long-Term Storage

Successful formulation development hinges on the ability to screen and identify excipients that stabilize drug products during long-term storage. Biophysical and accelerated stability studies are used to screen for excipients that stabilize protein drug products. However, these studies are not always predictive of aggregation during long-term storage. In this study, we used multivariate experimentation to compare the effectiveness of intrinsic fluorescence and size exclusion chromatography accelerated stability parameters to predict excipients that stabilized bovine serum albumin (BSA) against aggregation on long-term storage at 4 °C. Emission intensity ratio (IR_330/350) data was more sensitive than emission maxima (λ_max) or intensity measurements in identifying significant factors and interactions. We observed the expected inverse correlation between the mid-points of fluorescence thermal transitions (T_ms) and insoluble aggregates at 4 and 40 °C. However, there were positive correlations between T_ms and % aggregates at 4 °C, indicating that if T_m was used as a predictive tool, it would select formulations that promoted soluble aggregates on long-term storage. Ambient temperature IR_330/350 measurements identified excipients that reduced BSA soluble aggregates on long-term storage. The results show ambient temperature emission ratio measurements can be useful for protein formulation development.

Spectroscopic and structural studies, thermal characterization, optical proprieties and theoretical investigation of 2-aminobenzimidazolium tetrachlorocobaltate(II)

In this study we present the crystal structure, spectroscopic and thermal behavior, Hirshfeld surface analysis, and DFT calculations of a new organic-inorganic hybrid compound (C₇H₈N₃)₂[CoCl₄]. This compound crystallizes in the centrosymmetric space group P1¯. Single-crystal X-ray diffraction analysis indicates that structure consists of a succession of mixed layers formed by organic cations and inorganic anions parallel to the (001) plane and propagate according to the c-axis. Layers further are assembled into a 3D supramolecular architecture through N-H^…Cl hydrogen bonds and π^…π interactions. The peak positions of the experimental PXRD pattern are in agreement with the simulated ones from the crystal structure, indicating phase purity of the title compound. The presence of the different functional groups and the nature of their vibrations were identified by ATR-FTIR and FT-Raman spectroscopies. The tetrahedral environment of Co²⁺ was confirmed by UV-visible spectroscopy, where the spectrum shows three weak absorption bands in the visible range due to d-d electronic transitions ⁴A₂(F) → ⁴T₂(F), ⁴A₂(F) → ⁴T₁(F) and ⁴A₂(F) → ⁴T₁(P) typical of Co(II) coordination compounds. The direct and indirect optical band gap values were determined by Tauc method. The optimized structure and calculated vibrational frequencies were obtained by density functional theory (DFT) using B3LYP functional. TGA and DSC coupled to mass spectrometry (MS) experiments under argon atmosphere in the temperature range (25-950 °C) were carried out in order to determine the thermal stability of the title compound.

Synthesis, spectroscopy, crystal structure, TGA/DTA study, DFT and molecular docking investigations of (E)-4-(4-methylbenzyl)-6-styrylpyridazin-3(2H)-one

In this study, we present the synthesis of novel pyridazin-3(2H)-one derivative namely (E)-4-(4-methylbenzyl)-6-styrylpyridazin-3(2H)-one (MBSP). The chemical structure of MBSP was characterized using spectroscopic techniques such as FT-IR, ¹H NMR, ¹³C NMR, UV-Vis, ESI-MS, and finally, the structure was confirmed by single X-ray diffraction studies. The DFT calculation was performed to compare the gas-phase geometry of the title compound to the solid-phase structure of the title compound. Furthermore, a comparative study between theoretical UV-Vis, IR, ¹H- and ¹³C NMR spectra of the studied compound and experimental ones have been carried out. The thermal behavior and stability of the compound were analyzed by using TGA and DTA techniques which revealed that the compound is thermostable up to its melting point. Finally, the in silico docking and ADME studies are performed to investigate whether MBSP is a potential therapeutic for COVID-19.

Thermal analysis and enhanced visual technique for assessment of microplastics in fish from an Urban Harbor, Mediterranean Coast of Egypt

Enhanced visual counting technique coupled with combustion analysis and differential scanning calorimetry (DSC) was applied to assess microplastics (MPs) contamination in fish digestive tracts from Eastern Harbor, Egypt, to provide a simple and economic method for MPs assessment. This was the first study in Egypt to quantify MPs in fish. Plastic particles were detected in all fish samples, represented by seven thermoplastic polymers. The average number of MPs was at its highest level in Siganus rivulatus, Diplodus sargus, and Sardinella aurita (7527, 3593, and 1450MPs fish^-1, resp.) and the lowest in Sphyraena viridensis and Atherina boyeri (46 and 28MPs fish^-1, respectively). The average weight of MPs as measured by combustion ranged from 302mg kg^-1 in S. rivulatus to 2mg kg^-1 in Terapon puta.

Integrating anaerobic digestion and pyrolysis for treating digestates derived from sewage sludge and fat wastes

The coupling of biological and thermal technologies allows for the complete conversion of wastes into energy and biochar eliminating the problem of sludge disposal. The valorisation of fatty residues as co-substrate in a mesophilic digester of a wastewater treatment plant was studied considering an integrated approach of co-digestion and pyrolysis. Four digested samples obtained from co-digestion of sewage sludge and butcher's fat waste were studied by thermogravimetric analysis. The activation energy corresponding to the sludge pyrolysis was calculated by a non-isothermal kinetic. Arrhenius activation energy was lower for the pyrolysis of a digested grease sample (92 kJ mol^-1 obtained by OFW and 86 kJ mol^-1 obtained by Vyazovkin) than for the pyrolysis of sewage sludge and its blends (164-190 kJ mol^-1 obtained by OFW and 162-190 kJ mol^-1 obtained by Vyazovkin). The analysis of the integrated approach of anaerobic co-digestion and pyrolysis of digestates demonstrated that the addition of 3% (w/v) of fat to the feeding sludge results in a 25% increase in the electricity obtained from biogas (if a combined heat and power unit is considered for biogas valorisation) and increasing the fat content to 15% allows for covering all thermal needs for drying of digestate and more than doubles (2.4 times) the electricity production when the scenario of digestion and pyrolysis is contemplated.

Thermal behavior of food preservative sorbic acid and its derivates

Sorbic acid and its potassium and calcium salts used as food preservatives and sorbic chloride were submitted to thermal analysis in order to characterize their thermal behavior on heating and cooling processes, using TG/DTG/DTA, TG-MS, DSC, hot stage microscopy and DRX analysis. Sorbic acid melted and decomposed under dynamic heating. Under isothermal it sublimated without decomposition before melting (T < 134 °C). The potassium salt presented a solid-solid phase transition before decomposition. Both potassium and calcium salts decomposed in temperatures higher than the acid without melting, producing the respective carbonates and oxides as final residues. Sorbic chloride evaporate without condensation, on dynamic heating.

Molecular and functional characterization of unique thermo-halophilic thioredoxin from the metagenome of an exotic environment

The lower convective layer (LCL) at Atlantis II brine pool of the Red sea represents one of the exceptional, unique ecosystems. Thioredoxin is a multi-functional antioxidant redox protein that has a crucial role in various vital cellular processes. In the current study, a functional metagenomics approach was used to isolate and characterize thioredoxin from the LCL of Atlantis II Deep brine pool (Trx-ATII). From the metagenomic DNA of the LCL, the thioredoxin gene was directly retrieved and sequenced. Sequence analysis showed that the gene belonged to thioredoxin-like superfamily with classical Trx motif (-CXXC-). Phylogenetic analysis revealed that Trx-ATII was closely related to Trx of Prochlorococcus marinus with a maximum identity of 86%. Successfully, Trx-ATII was cloned and expressed in E. coli, where the purified protein had M.wt of 16 kDa. Characterization studies revealed that Trx-ATII protein is halophilic; can tolerate up to 2.5 M NaCl and thermostable, where 90% of its activity was retained at 60 °C. Trx-ATII can reduce both DTNB and insulin disulfide- containing substrates. In conclusion, a unique thioredoxin protein was isolated from a harsh environment that can maintain its activity under extreme conditions of salinity and temperature as a promising redox protein for biotechnological applications.

Exploring the role of lignin structure in molecular dynamics of lignin/bio-derived thermoplastic elastomer polyurethane blends

The relaxation behavior of two lignins (Alcell organosolv, OSL, and hydroxypropyl modified Kraft, ML) and bio-based thermoplastic polyurethane (TPU) blends have been studied by Differential Scanning Calorimetry (DSC), Dynamic-Mechanical Analysis (DMA) and Dielectric Relaxation Spectroscopy (DRS). The effect of blending on the glass and local relaxation processes as a function of composition, frequency, and temperature has been assessed. The dielectric spectra were resolved into dipolar relaxations as well as conductive processes for differing blend compositions. Characteristic relaxation times, activation energies and dielectric relaxation strengths of lignin/xTPU blends were also investigated. It was found that blending suppresses the α-relaxation process of the blends compared to virgin TPU. On the other hand, while the position of the β-relaxation was not influenced by blending, a reduction of the activation energies, Ea, of this process was observed in the lignin/xTPU blends. Finally, changes are observed in the conductivity behavior of both blends, with conductivity processes more favorable for the OSL/xTPU blends.

A variable temperature infrared spectroscopy study of NaY zeolite dehydration

Variable temperature diffuse reflection infrared spectroscopy is used to monitor molecular vibration changes associated with water molecules and zeolite framework during thermal dehydration of NaY zeolite. Absorbance bands are assigned to three unique water molecule environments. These three water types exhibit different temperature-dependent band intensity profiles. A band at 3700 cm^-1 is assigned to framework acid sites. The intensity of this band was found to vary with temperature in a manner consistent with the occupancy of sodium cations in II' unit cell locations. Specific framework vibrations exhibit temperature-dependent intensity change profiles. Band intensities at 1190, 1060, and 960 cm^-1, associated with Si-O-Si and Si-O-Al asymmetric stretching vibrations, are sensitive to water content. Band intensity at 800 cm^-1, assigned to Si-O-Si symmetric stretching, is inversely correlated with temperature-dependent unit cell volume changes. All framework band intensity changes detected during heating are reversible after re-hydration during sample cooling.

Experimental thermal analysis of a novel prosthetic socket along with silicone and PCM liners

Prosthetic liners and sockets insulate a residual limb, causing excessive heat, sweating, skin irritation and maceration. Circulation of a fluid through the socket wall has been shown to have positive cooling effects on the internal surface of the socket, i.e. skin temperature. Moreover, Phase Change Materials (PCMs) have been recognized as a practical method for cooling garments. These materials, such as water or many synthesized polymers, have a high latent heat and their application within a prosthetic liner allows for absorbing heat from the limb for retaining a constant temperature. In this study, a novel prosthetic socket has been designed and prototyped to investigate the interactive effects of fluid circulation and PCM materials on thermal comfort of prosthetic sockets. The results indicate a statistically significant difference (p-value < 0.001) in the duration a PCM liner can retain the appropriate skin temperature, compared to regular silicone liners. Likewise, the presence of air circulation within the socket wall was shown to have statistically significant influences (p-value = 0.018) on providing the efficient cooling effects compared to regular sockets. Hence, incorporating circulation cooling mechanisms along with PCM liners as proposed in this study holds a promising solution to enhance the thermal comfort of prosthetic socket systems.

Interactions of Perfluorohexyloctane With Polyethylene and Polypropylene Pharmaceutical Packaging Materials

Semifluorinated alkanes (SFAs) are aprotic solvents, which may be used as drug solvents for topical ocular applications, for instance, in dry eye syndrome. Their physical properties suggest that they might be prone to interaction with plastic materials, such as, polyethylene (PE) and polypropylene (PP), which are commonly used as packaging materials for pharmaceutical products. In this study, we investigate interactions of PE and PP with a liquid SFA perfluorohexyloctane (PFHO) using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and cross-polarized light microscopy. Binary phase diagrams of PFHO-PE and PFHO-PP systems demonstrating interactions of PFHO with the polymeric materials were constructed based on DSC data. According to this data, PFHO tends to lower the melting temperatures of PE and PP. The equilibrium values of solubilities of the polymers in PFHO and PFHO in the polymers were obtained by extrapolation of melting enthalpy data. Absorption of PFHO by PE and PP materials at ambient conditions after 4 weeks of equilibration was also studied by TGA. From the presented results, it may be concluded that thorough studies of interactions of PE or PP with SFAs are required when these materials are used as packaging components in SFA-based formulations.

Pyrolytic degradation of peanut shell: Activation energy dependence on the conversion

This study focuses on the thermo-kinetic analysis of solid peanut shell waste, through dependence of the activation energy with the conversion degree. Three model-free kinetics, Kissinger (K), Friedman (Fr) and Kissinger-Akahira-Sunose (KAS), were applied to thermogravimetric (TGA) data to calculate the effective activation energy E_α during a pyrolysis process. The results obtained by Kissinger's method showed that the pyrolytic breakdown pathway of hemicellulose, cellulose, and lignin in a ligno-cellulosic biomass is independent of the heating rate and can be described through a simple first-order kinetic reaction (f(α) = 1 - α). The thermo-kinetic behavior obtained by isoconversional methods (Fr and KAS) of the hemicellulose degradation shows a progressive and monotonic increase in E_α with the conversion, between ~140 and ~195 kJ mol^-1 with an average value of 172 kJ mol^-1, which reveals the competitive character of the process (multi-step process). Conversely, in the cellulose degradation, the dependence of E_α on α, shows the typical behavior of a reaction controlled by a single rate-determining step, with constant average E_α values of ~209 kJ mol^-1. Meanwhile, the lignin pyrolytic degradation shows an increase in E_α from ~220 up to ~300 kJ mol^-1 with the conversion, indicating that this stage is kinetically controlled by an energy barrier that comprises multiple and simultaneous processes. Finally, the kinetic analysis confirmed the absence of autocatalytic reactions (thermally auto-catalyzed process) during the pyrolysis, although the global process is highly exothermic.

Carbetapentane citrate

Carbetapentane citrate, a non-opioid centrally-acting antitussive drug, is a common treatment for cough associated with other diseases such as common cold and respiratory tract infections. Its mode of action is very close to that of atropine; since it acts at the level of the peripheral parasympathetic nerve endings. The drug reaches its maximum plasma concentration (C_max) 2h after administration, and it has a plasma half-life of 2.3h in case of oral administration. Due to its clinical importance, there are many analytical methods in the literature for carbetapentane determination. In addition, it is crucial to collect its analytical results in a single chapter so as to allow researchers to easily interpret their experimental data. Here, we provide the analytical profile of carbetapentane citrate with a brief description/interpretation of each analysis.

An overview of microplastics characterization by thermal analysis

Microplastics may be present in the environment as primary microplastics (manufactured) or secondary microplastics (result of the continuous degradation of larger plastic pieces into smaller fragments due to environmental, physicochemical and biotic factors). To fully understand the dynamics of microplastic particles and their environmental effects, harmonized, automated, cheap, rapid and reliable methodologies for sampling, extraction and characterization of microplastic need to be developed. This review focuses on the potential of thermal analytical techniques for microplastics characterization and highlights some of the new trends in this area.

Pyrolysis and combustion kinetics of Sida cordifolia L. using thermogravimetric analysis

Sida cordifolia L. (Sida) is an annual invasive plant that remains underutilized in Niger. The goal of this study was to characterize the thermal decomposition of Sida for its valorisation as a source of energy through thermogravimetric analysis (TGA). TGA was carried out under nitrogen and air atmospheres. Thus, five different heating rates were used as 10, 20, 30, 40, 50 °C min^-1. Kinetic and thermodynamic parameters were determined by isoconversional models of Kissenger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). The results showed that the average activation energy (Ea) of Sida calculated by KAS and FWO in pyrolysis was found to be 74.74 and 80.74 kJ mol^-1 respectively, while it was 51.08 and 58.91 kJ mol^-1 in combustion respectively. Kinetic and thermodynamic parameters such as Ea, ΔH, ΔS, and ΔG obtained by KAS and FWO show that Sida is a remarkable feedstock for bioenergy.

Thermal hazard investigation and hazardous scenarios identification using thermal analysis coupled with numerical simulation for 2-(1-cyano-1-methylethyl)azocarboxamide

Polymers are salient participants in the current world, and roughly more than 40%-45% of all industrial polymers were produced by free radical polymerization. Azo-initiators now have been the foremost radical initiator with the virtue of low tendency to undergo chain transfer reactions. Nevertheless, azo-initiators are readily to decompose and release an immense amount of heats and gases under elevated ambient temperature. 2-(1-Cyano-1-methylethyl)azocarboxamide (CABN) was deliberately picked as an example for identifying the hazardous scenarios in the application of azo-initiators. Initially, thermal analysis technologies were used to investigate the thermal decomposition characteristics of CABN, and selected decomposition mechanism functions were verified for the best-fitting thermokinetic model. Subsequently, thermokinetic-based numerical simulations were implemented to evaluate the thermal hazards of CABN under the ideal adiabatic scenario. Process safety parameters under adiabatic conditions including time to maximum rate as well as induction period were consequently retrieved. Furthermore, inherent safety recommendations for free-radical polymerization were established to forestall the process accidents in storage and the applications of azo-initiator.

A3B type unsymmetrical and amphiphilic phthalocyanines: Synthesis, characterization, thermal stability and aggregation studies

This study reports the preparation, analysis, aggregation statuses and thermal properties of five phthalocyanines. The preparation of all molecules includes two steps: the first step is the preparation of phthalocyanine precursor molecules (A and B coded phthalonitriles); the second step is the synthesis of one metal-free and four metalled phthalocyanines (A₃B-Co, A₃B-Cu, A₃B-H, A₃B-Ni, and A₃B-Zn coded compounds). Compound A holds a hydrophobic chain (cetyl alcohol); compound B holds a hydrophilic chain (tetraethylene glycol). Phthalocyanines include three hydrophobic chains and one hydrophilic chain (A₃B type phthalocyanine). Characterization methods which were used to determine the structure of these compounds are Fourier Transform Infrared (FTIR), Proton Nuclear Magnetic Resonance (¹H NMR), Carbon-13 Nuclear Magnetic Resonance (¹³C NMR), and Ultraviolet Visible (UV Vis) spectroscopies and elemental analysis. The phthalocyanines have high stability up to 260 °C as a minimum value. Aggregation statuses of the phthalocyanines change to the metal from the metal or to the solvent from the solvent.

Soybean hulls: Optimization of the pulping and bleaching processes and carboxymethyl cellulose synthesis

Soybean hulls, a co-product generated in high volumes, were used to obtain pulp and CMC. The pulping process was optimized with the aid of 1%, 2%, and 2.5% NaOH solutions at 90 °C for 2 h. A 22 central composite design was used in order to optimize the bleaching process and the CMC synthesis. Volumes of bleaching solution (VS) of between 55 and 65 mL/g at temperatures between 85 and 95 °C and VS of 70 and 75 mL/g at 95 °C were applied in the pulp bleaching process. The factors considered in the carboxymethylation were the chloroacetic acid mass (1.2-2.1 g/g) and the reaction time (192-228 min), at 63 °C. The soybean hulls contain 40.62% of cellulose and have a low lignin content. The pulping process was optimized when 1% NaOH was used at 90 °C/2 h and bleaching process applying VS = 75 mL at 95 °C/4 h. The pulps showed low lignin content (<6%) and the cellulose had a high degree of crystallinity. The SEM, 1H NMR, XRD, FTIR and TGA/DTG analysis results demonstrated that it is possible to synthesize CMC (DS = 1.45) by acetylating the bleached pulp with 2.1 g of chloroacetic acid for 192 min, at 63 °C.

Synthesis, Structural Characterization, Enzymatic and Oxidative Polymerization of 2,6-Diaminopyridine

Enzymatic polymerization of 2,6-diaminopyridine (DAP) compound in the presence of HRP (Horse radish peroxidase) and H₂O₂ (hydrogen peroxide) with Poly(DAP-en) with the structures of two different types of polymers obtained by the oxidative polymerization of Poly(DAP-ox) using H₂O₂ in an aqueous basic environment was illuminated by ¹H-NMR, ¹³C-NMR, FT-IR, UV-Vis spectral methods. GPC (gel permeation chromatography), TGA (thermal gravimetric analysis), DSC (differential scanning calorimetry), CV (cyclic voltammetry), fluorescence analysis and conductivity measurements to characterize the compounds and their electronic structure were examined. SEM analyzes were performed for the morphological properties of the compounds. As a result of the analysis, it was observed that the polymer obtained by enzymatic polymerization was better than the polymer obtained by oxidative method. It was observed that the results of the fluorescence measurements were better than Poly(DAP-en) in Poly(DAP-ox) emitting blue and green light. According to TGA analysis, the first decay temperatures for Poly (DAP-en) and Poly (DAP-ox) were calculated as 342 °C and 181 °C, respectively. The higher value of glass transition temperature for poly (DAP-en) confirms that the average molar mass is higher than 8650 Da for Poly (DAP-en) according to GPC analysis.

Crystallo-co-spray drying as a new approach to manufacturing of drug/excipient agglomerates: Impact of processing on the properties of paracetamol and lactose mixtures

The novel process of crystallo-co-spray drying of paracetamol and α-lactose monohydrate was investigated by varying the spray dryer inlet temperature and inlet feed solvent composition. A crystalline agglomerate was obtained with no change to the physical structure of either component throughout both investigations and with possible interactions between the hydroxyl groups of the α-lactose monohydrate and the amide and hydroxyl groups of the paracetamol detected. The percentage soluble fraction of the components in the inlet feed had the largest influence on the morphology of the final dried agglomerate. Low excipient soluble fraction resulted in an increase in paracetamol surface coating and high excipient soluble fraction produced agglomerates of highly mixed components. The use of crystallo-co-spray drying can serve as a method of producing an agglomerated blend of crystalline co-spray dried components leading to possible opportunities for process intensification with the reduction of process steps such as blending, agglomeration, drying and milling into one single stage.

Simultaneous thermal analysis of cationic, nonionic and anionic polyacrylamide

Polyacrylamide (PAM) and its derivatives are the most commercially available water-soluble polymers and are frequently used for the production of clay-polymer composites. The characterization of their thermal behavior and decomposition was carried out mainly under reduced conditions by using N₂, He or Ar gas flow.

The object of this study was to investigate the thermal decomposition of cationic (PAM_S,τ40Cl), nonionic (PAM°_S), and anionic (NaPAM_S,τ40) polyacrylamide under synthetic air (SynA) in detail using a thermogravimetry/differential scanning calorimetry (TG/DSC) system connected to a quadrupole mass spectrometer (MS). MS data indicated the release of NH₃, CH₄ and NO together with H₂O, CO₂ and NO₂ during decomposition. The gas release differed between the three polymers.

Stoichiometric calculations showed that PAM_S,τ40Cl and PAM°_S decomposed completely, while NaPAM_S,τ40 decomposed only partially and the Na present for charge balancing remained in the form of Na₂O.

The thermal decomposition of PAM_S,τ40Cl, PAM°_S and NaPAM_S,τ40 under SynA occurred via pyrolysis and oxidation reactions.